Half to william evans



(No Model.)

H. HOLMES.

PROCESS 0F DBPILATING EIDES 0R SKINS.

No. 593,660. Patented Nov. 16, 1897.

. gases.

UNrrnD STATES muon.

ATENT HENRY HOLMES, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR OF ONE-I-IALF TO WILLIAM EVANS, OF SAME PLACE.

PROCESS OF DEPILATING HIDES O R SKINS.

SPECIFICATION forming part of'Letters Patent No. 593,660, dated November16, 1897.

' Application filed December 22,1896. Serial No. 616,578. (Nospecimens.)

To all whom it may concern:

Be it known that I, HENRY HOLMES, a citizen of the UnitedStatcs,*residing at the city of Phi1adelphia,in the county ofPhiladelphia and State of Pennsylvania, have invented certain new anduseful Improvements in the Process of Depilating Hides or Skins, ofvwhich the following is a speciiication.

My invention has relation to a process whereby'hides/or skins may bedepilated in from eighteen to twenty-four hours and thoroughly preparedfor the subsequent operations of leshing and tanning.

Hitherto the usual mode whereby hides and skins were successfully andcompletely depilated and prepared for fleshing or tanning was that knownas the limingi process or method, wherein the hides or skins werecovered with a paint or layer of lime applied to both the iiesh and thehair sides and subjected to the caustic action of the lime for a periodranging from ten to fourteen days.

' My present invention is designed to accomplish ,the same end as theliming process above referred to and to thoroughly and completelydepilate the hide or skin in a materially less time-to wit, in fromeighteen to twenty-four hours.

In the carrying out of my invention I iirst subject the hide or skin tothe action of a bath consisting of a strong solution of sulfid ofsodium, the strength of the solution varying withv the nature ofthehideor skin to be treated, in an open vessel which will permit of theescape of noxious and destructive Then the hide or skin and solution areagitated by means of a paddle or paddles, after which the skin or hideis permitted to remain at rest in the solution for about ten or twelvehours, when the strength of the solution is gradually diluted while the-hide or skin remains therein, the caustic strength of the solutionbeing thereby gradually weakened until the hides or skins remain in abath of pure or substantially pure water. The result of this process isa hide or skin which is pulpy, porous, soft, and well adapted to undergothe subsequent operations of leshing and tanning. A

The nature and scope of my invention will be more fully understood fromthe following description, taken in connection with the accompanyingdrawings, forming part hereof, in which-e Figure l is a transversesectional view of an apparatus designed to carry the depilating processof my invention into eect, and Fig. 2 is a longitudinal sectional Viewof said apparatus.

Referring to the drawings, A represents a vat or tank, whichqispreferably cylindriform, having an opening extending longitudinallyacross the upper end. On the open upper end is mounted a shaft b,carrying a series of paddlesB and adapted to be revolved or rotated by abelt b2 and pulley B', as illustrated in Fig. 2. The shaft b iseccentrically located, so that the paddles will dip into the upperportion of a liquid placed in the vat and to one side ofthe verticalcenter of the vat. The rotation of the shaft b and paddles B, by reasonof the position of the paddles, will'cause a circulation of the liquid,as indicated by the arrows in Fig. l.

In the vat A is placed sulfid of sodium in solution of requiredstrength, and the hides or skins to be treated are submerged in thissolution and agitated bythe revolution of the paddles B. rllhe hidestravel in the liquid from the bottom of the vat along its sides to thetop of the vat,when they are pushed down by the paddles and along thesides of the vat to the bottom thereof. By this action of the paddlesthe hides or skins are thoroughly washed in the solution. At the side ofthe vat A is arranged a pipe cl, controlled by a cock or valve d', andadapted to discharge into the vat at or near its upper end a stream offresh water, and at the side ends of the vat are arranged a series ofvalve-controlled outlets c, adapted to permit of the discharge of thesolution in the vat. When the valve d is open and the outlets c are alsoopen, a curv rent of water enters the vat and mixes with the solution ofsodium sulfid therein and gradually dilutes it, the diluted mixtureflowing through the outlets c, thereby permitting of a still furtherdilution of the solution upon the entrance of more fresh water from thpipe d.

The operation of the apparatus is as follows: The solution of sodiumsuliid and the ICO hides or skins are introduced into the vat andsubjected to agitation by the paddles for a period of about half anhour. The hides or skins are then permitted to remain at rest in thesolution over night or for a period ranging from ten to twelve hours,when the hides or skins and the solution are preferably again agitatedby the paddles for a period of about two hours. During this secondagitation the valve d is opened to permit of the constant fiow of waterthrough pipe d, and hence the addition of fresh water to the solution ofsodium sulfid for the purpose of gradually diluting said solution, andat the same time the outlets c, of approximately the same area as thearea of pipe d, are also opened to permit of the escape of the solution.During the entire operation, the upper end of the vat being open, allnoxious and destructive gases are permitted to escape from the vat. Theconstant infiow of water and constant outfiow of solution are soproportioned to the bulk of solution in the vat that it requiresapproximately two hours to replace the solution in the vat with freshwater. Thus if the vat contains, say, four hundred and eighty gallonsthe infiow and outiiow should be approximately four gallons per minute.

From the description of the operation above set forth it will beunderstood that my depilating` process consists in certain well-definedsteps, which may be summarized as follows: first, the placing of thehide or skin in abath of sulfid of sodium of a required strength ofsolution; second, the agitation of the hide or skin and the bath for acomparatively short period of time; third, the subjection of the hide orskin to the action of the solution for from ten to twelve hours withoutagitation; fourth, the second agit-ation of the hide or skin and thesolution, and, fifth, the gradual weakening of the strength of thesolution by dilution during the second agitation until the bath in whichthe hide or skin is immersed becomes free or substantially free ofcaustic matter. Of allthese steps the fifth appears to be the mostimportant, for by it the hide or skin is subjected to a washing by asolution of gradually-decreasing strength, which solution washes outwhatever caustic matter remains in the substance of the hide or skin andwashes out or removes the dissolved hair and certain iibrous matters andbreaks up the gristle of the hide or skin, thus leaving the same pulpy,porous, soft, and well adapted to undergo the tanning and othersubsequent operations.

As far as l am enabled at present to understand, the chemical action ofmy process upon the skin is as follows: The solution of sulfid of sodiumof normal strength burns out and dissolves the nitrogenous and hairymatters and swells the skin, rendering it pulpy and porous, but fillsthe pores with caustic matter in a more or less undissolved state and inchemical combination with the substance of the skin. lf this causticmaterial were permitted to remain in the skin, it would speedily eat upthose matters which give to the finished leather its life or vitalityand would render the skin brittle, liable to split or break, andimperfectly susceptible to the tanning operation. By agitating the skina second time in the solution, which is gradually weakened by dilution,I am enabled to wash out this caustic matter, and at the same time thediluted solution appears to penetrate the body or substance of the skinand acts upon the gristly matter, which it breaks up and renders porous.The caustic matter, l believe, is dissolved by the weakened solution andis thus carried off as the solution escapes from the vat. The originalsolution should be of a strength varying from 2 to (5o Eaum test,according to the nature of the hide or skin to be treated, as well asthe uses to which the skin or its hair is to be put.

Having thus described the nature and objects of my invention, what lclaim as new, and desire to secure by Letters Patent, is-

l. The herein-described process of depilat ing hides or skins, whichconsists in subjecting the hides or skins to a bath, consisting of asolution of sulfid of sodium of required strength, then agitating thehides or skins and the solution for a relatively short interval of time,then subjecting the hides or skins to the action of the solution for acomparatively long period of time and without agitation, thenreagitating the hides or skins and the solution and finally graduallyweakening the strength of the solution by dilution during thisreagitation, substantially as and for the purposes described.

2. The herein-described process of depilating hides or skins, whichconsists in subjecting the hides or skins to a bath consisting of asolution of sulfid of sodium of required strength, then agitating thehides or skins and the solution, then aga-in subjecting the hides orskins to the action of the solution but without agitation, thenreagitating the hides or skins and the solution and at the same timegradually weakening the strength of said solution and finally permittingduring the entire operation the free escape of gases generated in ihesolution, substantially as and for the purposes described.

In testimony whereof I have hereunto set my signature in the presence oftwo subscribing witnesses.

HENRY HOLMES.

lVitnesses:

J. WALTER DoUoLAss, THOMAS M. SMITH.

lOO

